A cyclone dust-collecting apparatus, which whirls an external air and separates dirt from the external air using a centrifugal, has been used from long time ago. Particularly, a dual cyclone dust-collecting apparatus, which two sub-cyclone dust-collecting apparatus are installed in parallel to improve a dust separating or collecting efficiency, is also known already.
A large size dual cyclone dust-collecting apparatus is disclosed by Dyson et al. in EP patent publication No. 0018197. Two sub-cyclone dust-collecting apparatus of a large size are arranged in an upright type vacuum cleaner. However, such a large size dual cyclone dust-collecting apparatus is not used in the present time, since it is too large and inconvenient to use and has a complicated structure.
In recent, a dual cyclone dust-collecting apparatus, which is miniaturized to be applicable to a small size vacuum cleaner, has been disclosed in Japanese patent publication No. 2004-135700. However, the dual cyclone dust-collecting apparatus is configured, so that two sub-cyclone dust-collecting apparatus are horizontally arranged and a dust-collecting chamber is disposed below the two sub-cyclone dust-collecting apparatus. Accordingly, the dual cyclone dust-collecting apparatus enlarges in height and volume. In addition, the dual cyclone dust-collecting apparatus is configured, so that a flow of drawn-in air is abruptly bent at an angle of 90°, thereby increasing a loss in flowing passage and decreasing an inhalation force. Also, it is difficult to separate the dust-collecting chamber from the dual cyclone dust-collecting apparatus, and thus it is troublesome to dump dust from the dust-collecting chamber. Also, if the dual cyclone dust-collecting apparatus does not have a separate electrical measuring device installed therein, it is difficult to confirm an amount of dust from the outside.